ה֖' יִּלָּ חּם לָּּ כּם וְּאַ תּ֖ם תּֽחֲרִשֽׁוּן.
God will fight for you and you will be silent
Moshe's demand of silence from Am Yisrael is the same demand made of Moshe himself from Hashem
2ו יֹּ֤א מר הּ֙' אל מֹּ שּׁ֔ה מה תִּצְ עּק אלָּּ֑י ד בּר אל בְּנּֽ י יִּשְרָּ אּל וְּיִסָּּֽעוּ.
And Hashem said to Moshe "Why are you shouting to me? Speak to Bnei Yisrael, and they should move"
"Be silent Moshe!", but why should we all be silent? Why not pray? The Baal HaTurim tells us
This was a hint to Moshe that he will shout at me for forty days on the mountain, praying for Israel, and also the five words he will pray from Miriam "Please O God heal her ", because there is a time for long prayers and a time for short ones. Now is the time to be silent and not pray, just tell Bnei Yisrael to move
Moshe made two great prayers, the first was the longest ever, forty days, and the second, the shortest ever, just five words. Why should he be silent now?